The underlying mechanism(s) of opiate tolerance and dependence remains to be elucidated. Several theories have been postulated for such phenomena. However, recent findings of endogenous anti-opiate peptides (AOPs) like neuropeptide FF (NPFF), and an active phosphorylated opioid microgram receptor state suggest the involvement of a combined model to explain the development of opioid tolerance and dependence. The present project attempts to examine NPFF interaction in modulating the binding parameters (receptor density and affinity) and in mediating the signal transduction pathway of the opioid microgram recaptor system in the SH-SY5Y cells that are morphine tolerant. Cells will be made tolerant by being exposed to morphine sulfate at a 1 microgram M concentration for two days, which has been previously shown by measuring cAMP accumulation. Homogenate binding studies after NPFF and morphine exposure will be examined. In addition, the modulatory effects of chronic NPFF exposure in the presence or absence of a morphine tolerant state on cAMP accumulation, protein kinase C activity and endogenous phosphorylation activity will also be performed. The present project is designed to determine such interactions of NPFF during opiate tolerance at both the receptor and subcellular levels. The results generated from these studies will help to delineate the mechanisms by which NPFF attenuates the development of morphine tolerance. Furthermore, participation by two minority graduate students in the proposed project will enhance their career interests in biomedical research, while providing sound laboratory and experimental research skills.